To maintain costs as low as possible, EP printers are now designed to allow as much user maintenance as possible. To this end, dry toner EP printers enable a user to replace the toner cartridge which also contains an entirely new organic photoconductor-coated drum and related actuating mechanisms. EP printers which employ liquid toners are provided with refillable toner reservoirs, thus requiring the user to replenish the in-printer reservoir from a liquid toner supply. The user is thus exposed to possible spillage, vapors, and, with color printers, the possibility that a wrong color toner will be loaded into a reservoir.
Because liquid toners contain toner particles in a liquid carrier, the particles may settle to the bottom of the toner container unless provisions are made to either agitate the liquid toner or to provide means for its continuous circulation. Prior art printers have included liquid toner pumps and valve mechanisms for the recirculation of the liquid toner. Since such pumps and valves were part of the printer, their reliability was required to be equal to that of the printer. However, over a period of time, the liquid toner was found to coat the internal surfaces of the pump and valve mechanisms with a paint-like substance that eventually impaired their working parts.
Accordingly, it is an object of this invention to provide an improved, user-replaceable, liquid toner cartridge for an EP printer.
It is another object of this invention to provide an improved, user-replaceable, liquid toner cartridge which requires only two fluid connections.
It is yet another object of this invention to provide an improved, user-replaceable, liquid toner cartridge that incorporates mechanisms that are likely to fail prior to the end of the useful life of the printer.
It is still another object of this invention to provide a user-replaceable toner cartridge wherein all connections to the cartridge are automatically made upon insertion of the cartridge into a printer.